{"id":2949,"date":"2026-09-07T17:54:42","date_gmt":"2026-09-07T17:54:42","guid":{"rendered":"https:\/\/www.vikkins.com\/?p=2949"},"modified":"2026-09-07T17:55:18","modified_gmt":"2026-09-07T17:55:18","slug":"blast-freezer-panel-thickness-calculation","status":"publish","type":"post","link":"https:\/\/www.vikkins.com\/es\/blast-freezer-panel-thickness-calculation\/","title":{"rendered":"Blast Freezer Panel Thickness: Why \u221235\u00b0C Is Not Just a Colder Cold Room"},"content":{"rendered":"

<\/p>\n

\"Insulated
Panel thickness is the first irreversible decision in a cold store project. Once the envelope is built, the refrigeration plant spends the next twenty years compensating for whatever the envelope lets through.<\/figcaption><\/figure>\n

Blast freezer panel thickness is the first irreversible decision in a cold store project, and it usually arrives as two quotations on the desk for the same 20 \u00d7 15 \u00d7 5 m room. One specifies 100 mm panels. The other specifies 150 mm. The second is roughly 30% more expensive on the envelope line.The other specifies 150 mm. The second is roughly 30% more expensive on the envelope line.<\/strong><\/p>\n

The supplier offering 100 mm says it is “standard for freezer rooms.” The supplier offering 150 mm says the thinner panel “will not hold \u221235\u00b0C.” Both sound confident. Neither has shown you a calculation.<\/p>\n

There is a calculation, it takes about ten minutes, and it settles the question. More importantly, it exposes the assumption behind most of the expensive mistakes in this category: that a blast freezer is simply a cold room set to a lower number.<\/strong><\/p>\n

It is not. And the difference is not a matter of degree.<\/p>\n

The only two formulas you need<\/h2>\n

Heat moves through a panel at a rate governed by one property: thermal conductivity, written as \u03bb (lambda), in W\/(m\u00b7K). Every insulation core has one. Divide it by the panel thickness and you get the U-value \u2014 the heat that passes through one square metre for every degree of temperature difference:<\/p>\n

U = \u03bb \/ d<\/strong>
\nU in W\/(m\u00b2\u00b7K) \u00b7 \u03bb in W\/(m\u00b7K) \u00b7 d = core thickness in metres<\/span><\/p>\n

Then the heat flux through that panel is:<\/p>\n

q = U \u00d7 \u0394T<\/strong>
\nq in W\/m\u00b2 \u00b7 \u0394T = temperature difference across the panel, in kelvin<\/span><\/p>\n

That is the whole basis of panel selection. Everything else is applying it honestly.<\/p>\n

Declared thermal conductivity values, per the European product standards for each core type:<\/p>\n\n\n\n\n\n\n\n\n
Core material<\/th>\nDeclared \u03bb, W\/(m\u00b7K)<\/th>\nProduct standard<\/th>\n<\/tr>\n<\/thead>\n
PIR (polyisocyanurate)<\/td>\n0.022 \u2013 0.026<\/td>\nEN 13165<\/td>\n<\/tr>\n
PU (polyurethane)<\/td>\n0.023 \u2013 0.028<\/td>\nEN 13165<\/td>\n<\/tr>\n
EPS (expanded polystyrene)<\/td>\n0.033 \u2013 0.038<\/td>\nEN 13163<\/td>\n<\/tr>\n
Mineral wool<\/td>\n0.038 \u2013 0.045<\/td>\nEN 13162<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

One question worth asking every supplier:<\/strong> is the quoted \u03bb the initial value or the aged value? Closed-cell foams change over time as the blowing agent diffuses out. EN 13165 requires a declared value that accounts for ageing, but not every datasheet in circulation follows it. For a building with a twenty-year life, the aged figure is the one that matters. The worked examples below use 0.022 W\/(m\u00b7K) \u2014 the favourable end of the PIR range \u2014 so that the conclusions hold even for a good panel.<\/em><\/p>\n

Why \u221235\u00b0C changes the arithmetic, not just the setpoint<\/h2>\n

Take a plant in a tropical or subtropical location. Design ambient 30\u00b0C.<\/p>\n

    \n
  • Frozen store at \u221218\u00b0C:<\/strong> \u0394T = 48 K<\/li>\n
  • Blast freezer at \u221235\u00b0C:<\/strong> \u0394T = 65 K<\/li>\n<\/ul>\n

    That is 35% more temperature difference across the same wall. Since heat flux is directly proportional to \u0394T, the identical panel leaks 35% more heat the moment you drop the setpoint from \u221218\u00b0C to \u221235\u00b0C.<\/strong><\/p>\n

    Run it through with 100 mm PIR \u2014 U = 0.022 \/ 0.10 = 0.220 W\/(m\u00b2\u00b7K):<\/p>\n\n\n\n\n\n\n
    Tipo de habitaci\u00f3n<\/th>\n\u0394T<\/th>\nHeat flux q<\/th>\n<\/tr>\n<\/thead>\n
    \u221218\u00b0C store<\/td>\n48 K<\/td>\n10.6 W\/m\u00b2<\/td>\n<\/tr>\n
    \u221235\u00b0C blast freezer<\/td>\n65 K<\/td>\n14.3 W\/m\u00b2<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Now the reverse question, which is the one that actually decides the purchase. If 150 mm PIR gives an acceptable 7.0 W\/m\u00b2 in the \u221218\u00b0C store, what thickness gives that same 7.0 W\/m\u00b2 at \u221235\u00b0C?<\/p>\n

    U required = 7.0 \/ 65 = 0.108 W\/(m\u00b2\u00b7K)
    \nd required = 0.022 \/ 0.108 = 0.204 m \u2192 200 mm<\/strong><\/p>\n

    So the honest answer to those two quotations is that neither 100 mm nor 150 mm delivers, at \u221235\u00b0C, what 150 mm delivers in a conventional freezer store.<\/strong> Holding the same envelope performance at blast-freezing temperature takes roughly one thickness step more than most buyers expect \u2014 because they are anchored to their experience with \u221218\u00b0C rooms.<\/p>\n

    Doubling the thickness does not halve the loss<\/h2>\n

    This is where intuition fails most often, and where money gets wasted at the other extreme.<\/p>\n

    U is inversely proportional to thickness, so going from 100 mm to 200 mm does halve the conduction<\/em> through the panel. But conduction through the panel is only one component of the total refrigeration load. The others do not care how thick your walls are:<\/p>\n